Effect of tumor cell-derived debris and IgG on metastasis of pancreatic cancer and inflammation through tumor-associated macrophages.

Abstract

e15764 Background: The progression and metastasis of pancreatic ductal adenocarcinoma (PDAC) is highly dependent on the tumor microenvironment. Most tumor-associated macrophages (TAMs) are M2 phenotypic macrophages, which normally show anti-inflammatory functions in numerous disorders. We previously found that alternatively activated macrophages showed pro-inflammatory characteristics upon stimulation of hepatoma cell-derived debris, but the molecular mechanism was unclear. Methods: Macrophages were induced using tumor cell debris. Xenograft mouse model was established. Immunoblotting and immunochemistry were used to test protein expression. Results: The M2 macrophages-derived inflammation also existed in PDAC. We proved that the necrotic debris of PDAC cells induced potent IL-1β release by M2 macrophages via TLR4/TRIF/NF-κB signaling, and this effect was further boosted by IgG that also derived from PDAC cells. We further revealed that increased IL-1β promoted epithelial-mesenchymal transition (EMT) and consequent metastasis of PDAC cells. Using a selective COX-2 inhibitor celecoxib, we enhanced the anti-tumoral efficacy of gemcitabine. Conclusions: These data revealed a special pro-inflammatory phenomenon and mechanism in PDAC, and indicated that IL-1β and COX-2 can be therapeutic targets of anti-inflammatory strategy in PDAC treatment.